Curiouser and Curiouser
Update:
After further investigation, I've found that if I try:
select tbl, col, width, array_extent
from openquery(PROGRESS92, 'select "tbl", "col", "width", "array_extent" from "syscolumns_full" where tbl=''pr''')
order by tbl, col
Then I get 43 rows, one for each...